Ambulatory surgery: Room air versus nasal cannula oxygen during transport after general anesthesia

We compared outpatients transported to the postanesthesia care unit (PACU) while breathing room air to 2-4 L/min nasal cannula oxygen (O-2) to test th e hypothesis that routine supplemental O-2 during transport is not required after general anesthesia in an ambulatory surgery center. We also examined whether the arbitrary arrival PACU O-2 saturations of > 92% may be used to predict an infrequent incidence of subsequent significant desaturations (< 90%) in the PACU. One-hundred-ninety patients were randomized to receive e ither room air or 2-4 L/min nasal cannula for transport to PACU after recei ving general anesthesia. O-2 saturations were recorded before surgery, just before leaving the operating room, and upon arrival in the PACU. The lowes t O-2 saturation occurring in the PACU was also recorded. The mean arrival PACU O-2 saturation was 95.0 in the Room Air group, compared with 97.2 for the Nasal Cannula (NC group, a statistically significant difference (P < 0. 001). In the Room Air group, 20% had arrival O-2 saturations less than or e qual to 92%, and half of these (10%) had O-2 saturations < 90%. In the NC g roup, 6% had O-2 saturations less than or equal to 92%, of which one third (2%) were < 90% on arrival in the PACU. All of these initial desaturations were easily corrected with face-tent O-2 administration, deep breathing, or both. Subgroup analysis revealed that patients whose ages were 60 yr or ol der or those weighing 100 kg or more had lower arrival room air saturations than their younger or slimmer counterparts. In the Room Air group, only th ree 3.9%) of the patients that arrived in PACU with O-2 saturations > 92% h ad subsequent desaturations <90%, compared with seven (7.9%) in the NC grou p. We conclude that most adult patients undergoing ambulatory surgery can b e transported safely to the PACU breathing room air after general anesthesi a. However, patients whose age was <greater than or equal to>60 yr or weigh t was 100 kg, or for whom transient O-2 desaturation on transport may be ha rmful, should be transported while breathing nasal O-2 via nasal cannula.